[tutorials] Do not overwrite files of other tutorials:

Made ARM 256 core builds fail!

tutorials/multicore/mtbb101_fillNtuples.C

@@ -40,7 +40,7 @@ Int_t mtbb101_fillNtuples()
 
    // Create a random generator and and Ntuple to hold the numbers
    TRandom3 rndm(1);
-   TFile ofile("mp101_singleCore.root", "RECREATE");
+   TFile ofile("mpbb101_singleCore.root", "RECREATE");
    TNtuple randomNumbers("singleCore", "Random Numbers", "r");
    fillRandom(randomNumbers, rndm, nNumbers);
    randomNumbers.Write();
@@ -52,7 +52,7 @@ Int_t mtbb101_fillNtuples()
    auto workItem = [](UInt_t workerID) {
       // One generator, file and ntuple per worker
       TRandom3 workerRndm(workerID); // Change the seed
-      TFile ofile(Form("mp101_multiCore_%u.root", workerID), "RECREATE");
+      TFile ofile(Form("mpbb101_multiCore_%u.root", workerID), "RECREATE");
       TNtuple workerRandomNumbers("multiCore", "Random Numbers", "r");
       fillRandom(workerRandomNumbers, workerRndm, workSize);
       workerRandomNumbers.Write();